Lipovitellin from the crustacean, artemia salina. Biochemical analysis of lipovitellin complex from the yolk granules.

Abstract

The polypeptide, lipid, and carbohydrate components of the lipovitellin complex from anostracan crustacean, Artemia salina, have been investigated. The lipovitellin isolated from the yolk granules is a carotenoid.lipoglycoprotein complex, containing 3.3% carbohydrate and 8.6% lipid. About half of the carbohydrate fraction is mannose and the rest consists of galactosamine, galactose, and glucosamine. The lipid fraction contained 67% phospholipid and 33% neutral lipid. Phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine are three major phospholipid components and their relative ratio changes by developmental stages. The neutral lipid fraction is composed of mainly triacylglycerol and cholesterol. Two polypeptide chains are identified as apoprotein components of the lipovitellin complex. Their molecular weights are estimated by sodium dodecyl sulfate gel electrophoresis to be 190,000 and 68,000, respectively. The third polypeptide with Mr = 85,000 is a very minor component and exists in nonstoichiometric levels in the lipovitellin complex. On the basis of an apparent molecular weight of the lipovitellin complex determined by gel filtration chromatography, the dimeric lipovitellin form is suggested, each monomer of which contains one set of Mr = 190,000 and one set of Mr = 68,000 apoproteins. Each dimeric lipovitellin complex contains approximately 70 associated lipid molecules, of which about 4 are attributed to canthaxantin, and 100 bound carbohydrate molecules.